The USB (Universal Serial Bus) is a bus for connecting a computer to various electronic devices. This USB is a cable bus that encompasses two signal lines and two power supply lines. Many personal computers and their peripheral devices have an interface conforming to the USB.
The USB interface was a devised with a premise of a system in which one or a plurality of devices are connected to one host computer. These devices connected to the host computer via the USB are generally called USB devices.
When a USB device is connected to the host computer, the host computer assigns a unique address to the USB device. In addition, the USB device has a plurality of endpoints for terminating a communication between the USB device and the host computer. The host computer handles communication with these endpoints of the USB device.
A study is underway with regard to a compact portable electronic device with a plurality of functions. When connecting such a multifunctional portable electronic device to a host computer using a USB interface, it is necessary to provide a fixed endpoint for each function within the portable electronic device. However, the provision of such an endpoint for each function is not desirable in a portable electronic device that needs to be compact. There is also a situation that there is not such a great need to simultaneously use a plurality of functions in such portable electronic devices.